Brought to you by The Moonlight Library!After a battle where Cassie can’t tell if she killed a Hork-Bajir before or after Jake called them off, Cassie has had enough of being an Animorph. She quits. No more morphing, no more fighting, and hopefully no more nightmares of being the greatest land-based predator who ever lived (T-Rex) and killing a triceratops. That is, until a little girl called Karen who is really a Controller stalks Cassie they both get lost in the woods.Cassie gets to know the injured Yeerk Aftran, and they have many arguments over the morality of being a predator versus the morality of being a parasite. It’s really fascinating. Aftran is convinced she’s going to turn Cassie in and become a sub-Visser – but she’s not sure if Cassie is really human. And there’s a leopard stalking Karen. And Cassie is desperate for peace between the Yeerks and in a terribly misguided but ultimately positive move decides to trap herself as a caterpillar to get Aftran to free Karen. The theory behind this is that Yeerks are little more than intelligent worms, blind, utterly helpless in their natural state. And that’s what Aftran will be returning to.But while I’m amazed at Cassie’s resilience, there is one big freaking massive fucking plot hole the size of Kansas in this novel.Karen.Even with Aftran giving up Karen, that little girl is still the daughter of the bank’s boss. He’s not suddenly magically not a person of interest to the Yeerks for no reason whatsoever. Someone’s going to notice his daughter isn’t coming to the Yeerk Pool every three days. Someone is going to notice Karen is no longer a Controller. They might even take her dad and the rest of the family. And when she’s reinfested, the new Yeerk is going to know Cassie’s name, where she lives, and that she’s a frickin human who can morph, not an Andalite.Game over.But apparently the Yeerks are just like ‘oh well, this host that used to be ours is no longer important and neither is her father, the guy we originally wanted. We’ll just her go about knowing about the invasion. Sure, no problem.’The Yeerks do not like to lose. They would rather kill their hosts than let them get away.In case you’re wondering, Cassie is not trapped as a caterpillar. She goes through the ‘natural morphing’ and becomes a butterfly, which then means the morphing clock has reset and she can demorph. It makes a little sense.My favourite part of this book is the part where Aftran is completely right: being a parasite is no worse to being a predator. Sure, they take away the free will of their slaves, but predators actually kill things. I used to think there could be this truce reached where the Yeerks live in a human host but just don’t control anything, but upon my re-read I’ve realised that’s impossible. Once a Yeerk is in your head, they take control, even if they are a good Yeerk. They can relinquish control of single limbs or whatever, but not the whole thing. It’s just not possible. They’re a parasite, not a symbiote. But they have as much right to do what they naturally do as predators do to plants and other animals.This is one of my favourite Cassie books. It’s not preachy, but it does make you think about the Yeerks from a different angle. Cassie’s the perfect one for this adventure to happen to because she’s the only Animorph who would go so far to save one little girl. She’s the only one who struggles with her morals. She’s the only one who can ultimately make peace between the Yeerks and humans. She’s growing up.